| 摘要 |
An interferometric acoustooptic signal processor utilizing a circular antenna array to cover a 360 degree field of view. Each antenna element of the array is connected to an input port of a Butler matrix. The signals are phase shifted within the Butler matrix and applied to a multi-channel periodic Bragg cell, resulting in generation of one or more acoustic waves therein. A laser beam is used to illuminate the Bragg cell and is modulated due to interaction with the acoustic waves, resulting in diffraction of the laser beam and generation of a diffracted beam pattern output from the Bragg cell. A Fourier transform lens focuses the diffracted laser beam on a back focal plane at a point characterized by two perpendicular coordinates designating the input signal power spectrum and the angle of incidence in relation to the antennae, respectively. By utilizing a circular antenna array with a Butler matrix a full 360 degree field of view is obtained using only one 2-D acoustooptic signal processor and the peak sidelobe to mainlobe level is reduced up to -30 dB. Furthermore, the accuracy and resolution of the processor are independent of frequency. |
